StreamPro ADCP Operation Manual - global site

StreamPro ADCP Operation Manual13 GlossaryIf, after reviewing this section, you are unable to find the word/jargon inquestion, please send us an e-mail containing that word. Your questionswill ensure that our glossary remains an effective reference tool for our customers.------ A ------Acoustic Doppler Current Profiler (ADCP): An instrument that obtainsprofiles of water velocity by transmitting sound of known frequency intothe water and measuring the Doppler shift of reflections from scatterers,which are assumed to be passively moving with the water.Acoustic Window: A covering for the hull-side opening of a sea chest thatis transparent to sound. A vessel mounted ADCP is typically mounted in asea chest and the acoustic window helps to isolate it from biofouling organismsand also the flow noise generated by the vessel.ADCP: Acoustic Doppler Current ProfilerADCP Coordinates: Profile data is reported in an orthogonal coordinatesystem as referenced to the instrument. Beam 3 is forward. Sideways is tothe right of forward (beam 2 for a down-looking ADCP, beam 1 for an uplookingADCP).Ambiguity: ADCPs determine the radial motion between a source and scattererby measuring the phase change of the reflected signal. Because phaseis periodic, this solution is multi-valued. For example, all three of the displacementsshown below will return the same phase measurement, whichresults in ambiguity:Ambiguity Resolution: A method to count the number of wavelengths includedbetween two points where phase is measured, thereby removing theambiguity associated with measuring only phase.Ambiguity Velocity: The maximum allowable radial motion for phasemeasurements to be unambiguous, corresponding to a maximum observablevelocity, beyond which ambiguity resolution is required.Autonomous Underwater Vehicle (AUV): An unmanned submersible withpropulsion, generally capable of navigation and accomplishing specifictasks (such as data gathering).page 98Teledyne RD Instruments